https://github.com/n0-computer/hello-iroh-ffi
https://github.com/n0-computer/hello-iroh-ffi
Last synced: 18 days ago
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- Host: GitHub
- URL: https://github.com/n0-computer/hello-iroh-ffi
- Owner: n0-computer
- License: mit
- Created: 2026-05-15T15:30:53.000Z (2 months ago)
- Default Branch: main
- Last Pushed: 2026-06-15T19:23:39.000Z (about 1 month ago)
- Last Synced: 2026-06-15T21:18:15.254Z (about 1 month ago)
- Language: Kotlin
- Size: 540 KB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Hello Iroh FFI
A minimal presence demo over [iroh](https://github.com/n0-computer/iroh), implemented in parallel on iOS/macOS and Android. Each platform is a self-contained app that speaks the same wire format, so a Swift peer and a Kotlin peer can share a screen.
| Platform | Language | Status | Details |
|---|---|---|---|
| iOS + macOS | Swift / SwiftUI | working | [swift/README.md](swift/README.md) |
| Android | Kotlin / Jetpack Compose | working | [kotlin-android/README.md](kotlin-android/README.md) |
| Console reader | Python | working | [python/README.md](python/README.md) |
| Console reader | JavaScript (Node) | working | [js/README.md](js/README.md) |
Both implementations consume [iroh-ffi](https://github.com/n0-computer/iroh-ffi) from public registries: Swift Package Manager on Apple platforms, Maven Central on Android. No Rust toolchain or local iroh-ffi checkout is needed. Read more about the language bindings at [docs.iroh.computer/languages](https://docs.iroh.computer/languages).
## How the demo works
Each peer controls one dot in a shared coordinate space. You move your dot by tilting the phone or dragging on the desktop, and you stream its position to the other peer at ~60 Hz over an iroh bi-directional stream. The peer renders your dot at the same coordinates next to its own, so both screens show the two dots tracking each other in real time.
The two peers are fully symmetric. There is no game, no score, and no authority role: each side sends its own position and renders the other's. Discovery is manual: copy your endpoint id, paste it on the other peer, tap Connect.
While connected, a line under the status shows the connection's live network paths — direct vs relay, remote address, and RTT — so you can watch iroh hole-punch its way from a relayed connection to a direct one.
### Wire format
A single bi-directional stream carries one frame type, sent continuously by both peers:
| Frame | Size | Layout |
|---|---|---|
| Position | 8 B | `f32 x, f32 y` |
Both coordinates are in `[-1, 1]`, little-endian, and shared directly: the peer renders your dot at the position you send. With only one message type there is no tag byte, so the receive loop reads a fixed 8 bytes per frame.
ALPN: `iroh-helloiroh-dot/0`.
## Repo layout
```
hello-iroh-ffi/
├── README.md
├── demo.gif
├── swift/ iOS + macOS app (Swift / SwiftUI)
├── kotlin-android/ Android app (Kotlin / Jetpack Compose)
├── python/ headless console reader (Python)
└── js/ headless console reader (JavaScript / Node)
```
## Further reading
- [docs.iroh.computer](https://docs.iroh.computer) — iroh concepts and language guides
- [iroh-ffi](https://github.com/n0-computer/iroh-ffi) — Swift, Kotlin, Python, and Node bindings
## License
[MIT](LICENSE)